In recent years, because of the environment protection concern, liquid crystal display (LCD), due to having advantages such as higher quality, better space utilization efficiency, lower power consumption and emitting no radiation, has become one of the mainstream products in the display industry. Basically, a liquid crystal display is constituted by a LCD panel and a backlight module; wherein, the backlight module is configured to provide light to the LCD panel, and accordingly the LCD panel can display a desired image.
In general, the backlight module includes a light source, a reflective film, a variety of optical films (for example, diffusion film, prism sheet, etc.) and a frame. FIG. 1A is a schematic view of an optical film in a conventional backlight module. FIG. 1B is a schematic partial cross-sectional view of the conventional backlight module assembled with the optical film shown in FIG. 1A. It is to be noted that FIG. 1B only illustrates a portion of the conventional backlight module 100 which includes a back plate 110, a frame 120 and an optical film 130. The back plate 110 includes a positioning part 112; the optical film 130 includes a lug 132 with a positioning hole 131; wherein the positioning hole 131 of the lug 132 is corresponding to the positioning part 112 of the back plate 110. As shown, by inserting the positioning part 112 of the back plate 110 through the positioning hole 131 of the lug 132, the optical film 130 can only obtain a limited amount of horizontal movement relative to the back plate 110. In addition, the optical film 130 can also obtain a limited amount of vertical movement relative to the back plate 110 through being fixed between the frame 120 and the back plate 110. As such, the optical film 130 is prevented from separating from the back plate 110.
Conventionally, the positioning part 112 is either a copper pillar buried in the back plate 110 or an accordion-shaped wall formed on the back plate 110. If the positioning part 112 is a copper pillar, the process of burring a copper pillar in the back plate 110 is not only time consuming and costly, moreover, the optical film 130 may be damaged by a single-point force while being assembled to the copper pillar. Alternatively, if the positioning part 112 is an accordion-shaped wall, a reserved space allowance is required and accordingly it is difficult to properly bend the positioning part 112 according to the position and aperture of the positioning hole 131 of the optical film 130; and thus, dust issue may consequently occur.
Moreover, the positioning part 112 can only prevent the optical film 130 from having a horizontal movement relative to the back plate 110; in other words, the positioning part 112 must be used with the frame 120 so as to prevent the optical film 130 from obtaining a vertical movement. Because using the positioning part 112 to prevent the optical film 130 from having a horizontal as well as vertical movement, the backlight module 100 accordingly has a larger thickness, and consequently, the display device adopting this backlight module 100 cannot have a compact size and a slimmer frame.